Photomechanical reproduction of pictures



H. E. IVES PHOTO MECHANICAL REPRODUCTION OF PICTURES Flled Sept 29, 1924 Nov. 15, 192 7.

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UNITED TA ES v 1,649,309 PATENT OFFICE.

HERBERT E. IVES, or MoN'rcL'AIR; NEW JERSEY, ASSIGNOR TO WESTERN ELEcrnfc" COMPANY, INCORPORATED, on NEW YORK, n. Y A conroRA'rIonoF-NEw'YoRx.

PHOTOMECHANICA L REPRODUCTION 01 PICTURES.

This invention'relates to photo mechani-- cal reproductions of pictures, and more especially it has to .do with the reproductionof pictures suitable for photo engravings,

such as are used in connection with newspaper reproductions.

Experience has proved that to provide picture reproductions suitable, for news print work, which are usually reproduced on copper or zinc plates by a photo engraver, it is necessary to make a half tone picture. According to the present practice, this work may be accomplished photographically in a number of different ways.

{5 The chief, objection to this practice is the skill required for performing the necessary photographic operations which, obviously,

is expensive.-

It is the object of the present invention to accomplish the reproduction of pictures suitable for printing purposes in an efiicient and practical manner. 1

According to one embodiment of \the invention, the characteristicswf the picture designated by the different elemental tone values thereof, are impressed on an amplifier modulator set which acts to impress currents characteristic of the elemental tone values or density of the picture on a light controlling device. The light controlling 1 device functions to' control the exposure of a photo sensitive surface and reproduce the picture in the form of a plurality of lines of uniform density and varying width. Such making a half tone zinc or copper plateas is commonly used in connection'with newspaper reproductions. The invention also providesfor the reproduction of the pictures in the form of dot images, similar in appearance to half tone pictures, so well known in the printing art.

A better understanding of the invention may be had from the following description, when taken in conjunction with the accompanying drawing, which illustrates only so much of the system and apparatus as is necessary for a clear understanding of the invention.

Fig. 1 illustrates the apparatus and circuit connections according to one embodiment of the invention. Fig. 2 is a detail of the light controlling device. Fig. 3 shows the variable density screen. Fig. 4 shows the sectored disk, r

a reproduction is particularly suitable for .to effect the closure of circuits extending Application filed September 29, 1924. Serial No. 740,542.

Referring now to Fig. 1, a drum 9. of suitable transparent material has mounted thereon a transparency 8 of the picture to be reproduced and is adpated to be moved by power communicated thereto' from a continuously rotating motor 10. The drum 9 is mounted on a shaft 11 which is carried by a longitudinally movable carriage112 and receives its power from the motor 10 through gears 18 and 19. Carriage 12 slides. on grids secured to a frame 13. The gear 18 is slidably mounted on the shaft 15 which is threaded for a portion of its length and [which passes through a sleeve mounted on the carriage 12. The shaft 15 isdriven by power imparted thereto from the motor 10 through suitable gearing and friction clutch mechanisms. The gearing mechanism comprises a pinion 20 mounted on the motor shaft and a gear 21 which is secured to shaft 15. Disposed on opposite sides of the gear 21 are disks of'friction material 22 and 23, such as wood ,or the like. In engagement with and fastened to the friction disk 23 is a collar'24 which is capable of being moved longitudinally along the axis of the shaft 15 but which rotates with the gear 21 due to the arrangement of a key. Associated with the collar-24 is a. ring 25 which is mounted on the armature of an electromagnet 26. Upon the energization of this magnet, the ring 25 is moved so as to cause the engagement of the friction disk 23 with the gear 21. When this condition is brought about, power from the motor 10 is imparted to the shaft 15, thereby causing its rotation.

Also mounted on the shaft .15 and rotatable therewith is a second drum 30 which has mounted thereon a photo sensitive surface or film 31. It is upon this photoi sensitive surface or film 31 that the picture appearing on the transparency 8 is to be reproduced either in the form of lines of uniform density and varying width or dot-images, such as are commonly employed fornewspaper reproductions.

In order to effect the automatic stopping of the shaft 15 upon the completion of a picture, a switch 35, which may be moved either to switch elements 36 or 38, is provided. The switch elements 36 and 38 are arranged in the path of the carriage 12, that is, when the carriage 12 is in its extreme right hand position, switch element 36 is operated for opening its associated contacts. Conversely, when the carriage 12 is in its extreme left hand position, the switch element 38 is operated and its associated contacts thereby opened. The opening of either the contacts associated with the switch elements 36 or 38 effects the opening of the energizing circuit of electro magnet 26. Upon the deenergization of the electro magnet 26,.the collar 24, together with the frietion disk 23, is'moved out of engagement with the gear '21, at which time the shaft 15 will be brought to rest.

Located within the drum 9 and responsive to the amount of light applied thereto in accordance with the optical transmission of .the picture 8 is a photo sensitive device 40. The photosensitive device 40 receives light from the light source through a condensing lens 46, a screen 47 and the transparency 8. Connectedto the respective electrodes of the photo sensitive device 40 is an amplifier set 50 which comprises a plurality of vacuum tubes 51, 52 and 53.- The characteristics of the amplifier set are well understood, and since it does not form a part of the present invention, further description of this particular part of the system is believed unnecessary.

Connected to the output circuitof'the amplifier 'set 50 is alight controlling valve 55. The light valve 55 is similar in general arrangement to the light valve disclosed in a copending application of R. C. Wente, Serial No. 635,886, filed. May 1, 1923. For more detailed information with reference to the particular and characteristic construction of the light valve, reference should be had to the .referred to application As shown in Fig.

2, the light valve comprises a conductor 56, which is suitably connected to the output circuit of the amplifier set 50 and which is arranged in a magnetic field supplied by magnet. 57. Depending upon the amount of current passing through the conductor 56, apertures controlled thereby will be opened and closed. For controlling the amount of light applied to the photo sensitive surface 31, this light is supplied'from an incandescent lamp 59 through a. condensing lens 60, the light controlling device 55, lens 61, sectored disk 63 and the variable density screen 62. The sector disk 63 and the variable density screen 62, together with a suitable lens 64, posi tioned to form an image of the lens surface 61 on the film as shown in Figs. 3 and 4, respectively, serve to break up the photo graphic impression, which is determined by the operation of the photo sensitive device 40, in accordance with the elemental tone value or density of the picture into dots. In the event that it is not desired to produce a dot image of the picture, the sectored disk 63, as well asthe variable density screen 62, and lens 641 may be dispensed with and the lens 61 so positioned as to form an image of the light valve opening on the film in which case the picture will be reproduced on the photo sensitive surface or film 31 in the form of parallel lines of uniform density and varying width. P

As shown in Fig. 3, the variable density screen 62 has a transmission range from a maximum at its centre to a minimum of practical opacity at its edges. The graduated image which will be thrown upon the photo sensitive surface or film 31 through the screen 62, corresponds to the graded image caused by, each aperture of the half tone screen due to the formation of a penumbra owing to the finite distance between the half tone screen and the condensing lens. This graduated image becomes by the processes of photographic development used in the preparation of half tone negatives, a well defined dot, whose area is proportional to the intensity of the light app i ed thereto.

The variable density screen 62 is periodi- I cally illuminated each time that light from source 59 passes through the slots in the sector disk 63. The relative rotation of the sector disk63, which is rotated in accordance with the rotation of the drum 30, is so fixed that the dots are suitably'positioned on the photo sensitive surface or film 31.

Various other methods of producing dot images suitable for news print work in place of the sector disk 63 and the variable density screen 62, may be used with equally good results. Other methods for accomplishing this feature are disclosed in my copending applications Serial No. 683,632, filed December 31, 1923 and Serial No. 733,464, filed Aug. 22, 1924.

The operations incident to the reproduction of a picture suitable for news print work are as follows:

Assume, for the sake of illustration, that the carriage 12 is in its extreme left hand position and that the switch 35 isin its central or neutral position. Under'these conditions, the electromagnet 26 is deenergized and the shaft 15 is stopped that a picture, which is in the form of a transparency, is mounted on the drum 9. The switch 35 is now thrown to its right hand position, whereupon a circuit is completed for causing the energization of the electro- Suppose, now,

magnet 26. Due to the energization of the The photo sensitive device 40 responds in accordance with the different elemental tone values of the picture and impresses on the amplifier set 50 a current: characteristic of the various elemental tone. values of the transparency 8. These currents, upon being received by the light controlling device 50, cause the illumination of the photo sensitive surface or film 3lito reproduce the various elemental tone values of the transparency 8.

Through the use of the sector disk 63, the

variable density screen 62, and a suitable lens 64, a-dot image of the picture appearing on the transparency 8 is reproduced on the photo sensitive surface or film 31, which is in a form particularly suitable for news print reproduction. It may also be desired to reproduce the icture in the form of parallel lines of varia le width and uniform density, in which case the sector disk 63,'the variable density screen 62 and the lens 64 are dispensed with. The operation incident to the reproduction of the picture will be the same as previously described.

Near the completion of the reproduction of the picture, in which case the carriage 12 will be in its right hand position, switch element 36 is operated for opening the associated contact. The opening of the associated contact causes the-deenergization of the electromagnet 26 and the stoppage of shaft 15. The apparatus may now be employed for ,the'rep'roduction of another picture. 1

Although the invention has been disclosed and- ,dBSCIlbfid with reference to a particular system, 1t s, of course, obvious that various modifications may be made without departing from the scope and spirit of the present invention.

What is claimed is:

1. In combination, a first rotatable. drum a second rotatable drum, a common driving shaft for saiddrums, a picture'film mounted on the first drum, a reproducing film mounted on the second drum, a light responsive device associated with the; first drum and adapted to enerate currents corresponding to successive elemental areas of the picture, a light valve associated with the second drum, means for applying said currents to saidvalve to operate the same, and means efi'ective in response to theoperation of said valve for exposing the reproducing-film in successive discrete areas to light varying in intensity from the center to the-edges of each area, said last mentioned means comprising a graded density screen and light interrupting means interposed between said valve and the reproducing film.

a 2. In combination, a driving shaft, :1. first drum carrying a picture transparency, a second drum carrying a photosensitive record blank, both of said drumsbeing-adalpted to be rotated by and to move axially along said driving shaft, a source of light associated with each drum, means for rotating said shaft to present corresponding areasof the picture and the record blank to their associated light sources, light responsive means for generating currents characteristic of the tone values of the picture'area's'exposed to the light, a light valve, means for applying 1 said currents-to said valve to operate the same, means efi'ective responding to the operation of said valve for illuminating each successive elemental area of the record blank to light, and means between said blank and said valve comprising a graded density screen and a light interrupter for causing duce currents corresponding to the tone.

values .of successive" elemental areas of the icture, a light valve adapted to be operated ysaid currents to correspondinglyaexpose elemental areas of the record blank, and means comprising a light interrupter and a screen graded indensity' from the center to the edges for causing each elemental area of "the record blank to be illuminated non:

uniformly from the center to the edges.

4. In combination, a transparent drum, a

picture film mounted on said transparent drum, a second drum carrying a photosensitive record blank, a common shaft for driving both of said drums, a light responsive device within said transparent drum adap-.

ted to generate currents corresponding to the elemental tone values of the picture, a light valve, alight bafiie with an opening llll therein to be uniformly illuminated by the light/rays passed through said valve, means between said baflle and said blank comprising a screen varying in density from the center to the edges for producing'on said blank an image of said opening, said image varying in brightness from the center to theedgesthereof, and a revolving light interrupter for interruptingtsaid image at a predetermined frequency.

5. In combination, a shaft, a pairlof drums mounted on said shaft, a source of light associated with each drum, means for v supplying continuous rotatory motion to said shaft to simultaneously bring corre spondiug areas of said drums into registry with light rays from the associated, light sources, a picture film carried by one of said drums, a photosensitive film carried by the other of said drums, means for producing currents characteristic of the elemental areas of the picture film, a light valve operated by said currents for causing exposure of successive elemental areas of the photosensitive film to lightfrom the associated source, a screen varyingin density from the center to the edges, and a light interrupter \for periodically interrupting the light rays incident on the exposed areas of the photosensitive film.

6. In a system for reproducing pictures suitable for photo-engraving process, a transparent drum, a transparency of the picture mounted on said drum, a light operateddevice located within said drum and responsive in accordance wi h the elemental tone values of the picture or producing a current characteristic of such elemental tone values, a source of light, a light valve connected with light operated device through a local circuit and operated by the current produced thereby, means to vary the aperture of said valve in accordancewith the current impressed .on said. local circuit,' a graded density screen in the path of the rays from the light valve for producing an image of density varying from center to edge, and means for interrupting the light incident on a photo-sensitive surface through the oper ation of said light valve.

In witness whereof, I hereunto subscribe my name this 25th day of September A. D., i

HERBERT E. IVES. 

